code: def is_polars_dataframe(v):
      return polars and isinstance(v, polars.DataFrame)
  
file_path: lets-plot/python-package/lets_plot/_type_utils.py
imports: import json
  import math
  from datetime import datetime
  from typing import Dict
label_desc: Use image node_id 2 for calling a global function with example usage: is_polars_dataframe(v) and returns: unknown